Husband of Lady Margaret de Holand and father of: Lady Joan de Beaufort, Lady Margaret de Beaufort, Henry de Beaufort, John de Beaufort, Thomas de Beaufort, and Edmund de Beaufort. He was invested as a knight, Order of the Garter (K.G.) circa 1397, and his illegitimate birth was legitimized by Parliament and Papal decree February, 1397. He became the 1st Earl of Somerset on 10 February, 1397, and the 1st Marquess of Somerset on 29 September, 1397. He was deposed as Marquess of Dorset and Somerset on 3 November 1399.∼John Beaufort, 1st Marquess of Somerset and 1st Marquess of Dorset, later only 1st Earl of Somerset, KG (c. 1371 – 16 March 1410) was an English nobleman and politician. He was the first of the four illegitimate children of John of Gaunt (1340-1399) (third surviving son of King Edward III) by his mistress Katherine Swynford, whom he later married in 1396.
Margaret de Holland de Beaufort
1385–1439 (m. 1397)